ECONOMIC USK OF HYDROCYANIC ACID GAS 7 



August of that year the San Jose scale (Aspidiotus per- 

 niciosus Comstock) was found at Charlottesville, Va., 

 on the grounds of Dr. C. H. Hedges. This was the 

 first discovery of this pest east of the Rocky Moun- 

 tains, and naturally caused a good deal of apprehen- 

 sion on the part of fruit growers all over the country. 

 Again Mr. Coquillett was detailed by the United States 

 Department of Agriculture to conduct experiments 

 with hydrocyanic acid gas on these infested trees. The 

 work was begun and completed in March, 1894. 



The gas process was not, however, generally 

 recommended for the fumigation of deciduous trees. 

 From the experiences of growers in California I felt 

 certain that the gas could be applied equally as suc- 

 cessful to deciduous fruit trees in the Bast and else- 

 where, if properly handled. With practically nothing 

 as a guide, except the general work done in California, 

 and little or no encouragement from leading Eastern 

 entomologists, I began a series of experiments, in the 

 spring of 1897, upon young plum, pear, apple, and 

 nectarine trees. The results of these preliminary ex- 

 periments were so very satisfactory that I was prompted 

 to continue my work on bearing trees in the fall of 

 1897. With the aid of Robert S. Emory, of Chester- 

 town, Md., a successful fruit grower, we perfected an 

 outfit and completed the first successful fumigation of 

 a large orchard in the East. The results of this work 

 were watched with much interest in this and other 

 countries. While the methods of generating the gas 

 have not been materially changed, the amounts of 

 chemicals have been adapted to suit conditions. The 

 apparatus for containing the gas has bee"n improved, 



